


Vanilla

by amamiya_toki



Category: IDOLiSH7 (Video Game)
Genre: Age Difference, Alpha/Beta/Omega Dynamics, Alternate Universe, M/M, Male Futanari, Mild Incest, Rape/Non-con Elements
Language: English
Status: Completed
Published: 2016-10-25
Updated: 2016-10-25
Packaged: 2018-08-24 15:52:56
Rating: Explicit
Warnings: Rape/Non-Con, Underage
Chapters: 1
Words: 3,988
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/8378155
Author URL: https://archiveofourown.org/users/amamiya_toki/pseuds/amamiya_toki
Summary: Nanase Riku was born an Omega with a very unusual condition which makes him experience heats even as a child. Usually, his doting big brother would be there to take care of things, but what if he is not around? Gaku learns the hard way.





	

**Author's Note:**

> I was going to complete impure love first, but [@orpheusheart](http://archiveofourown.org/users/orpheusheart/works) poisoned me with Omegaverse i7 and I got plot bunnies (Kinako) tossed my way from a friend so I decided to give it a try. The title was something I came up with randomly.
> 
> Do note that her Omegaverse details differ from the usual ones you would read in manga and such, so don't be afraid to ask if any details need to be clarified. It's pretty complicated, so I hope I explained everything properly?
> 
> Also, Riku here is 10 years younger than Tenn. And it rhymes! Jokes aside, I feel like I've sinned so badly that not even going to confession will prevent my going to hell. At least I won't be going to purgatory?
> 
> Enjoy!

This is not good.

That was the first thought that came to Yaotome Gaku's mind as he found himself in what was probably the worst situation he had ever faced in his entire twenty-two years or so of living.

To explain what was going on, the explanation will start from the very beginning.

His group-mate, who was then known as Nanase Tenn, left home when he was only thirteen. Along with him, he brought his beloved younger brother Riku, who was born with an unusual condition: unlike other Omegas who began releasing pheromones when their sexual organs develop during puberty, the child would be able to produce them even in his early childhood. However, at that time, the family had some financial issues. Despite having other options available to earn some keep, their parents began devising ways to make use of their younger son. Omegas were rare, male ones even more. Him being infertile made their plot even more feasible.

Learning of this, Tenn was devastated. How could a parent think of doing something so terrible to their child? However, protecting his dear brother was the only thing in his mind and he decided to leave home. Fortunately for him, he had a place to go. A man named Kujou Takamasa once spoke to him about his talent in singing and dancing, offering to groom him into a star. He had initially refused as he did not want to be separated from his younger brother, but he was left with no choice. With the condition that the man would not bring or do harm to Riku, the two were formally adopted into the Kujou family.

Years later, the idol group TRIGGER was formed and its three members were to live together in one apartment. Tenn was allowed to bring his beloved brother with him, as the boy refused to be separated from him.

However, as Riku grew older, the complexity of his condition also increased. His body's inability to regulate the production of certain hormones would cause him to go into heat, and when he does he also releases unusually strong pheromones. Unfortunately, existing treatments and medication had no effect on him. All that could be done was to observe and control other hormones that could possibly have any affect on his growth.

Being the overprotective older brother he was, Tenn did not allow Riku to study in a school like other children his age. Instead, he sourced for a private tutor, one who was also an Omega, to teach the child at their apartment. He managed to find Izumi Mitsuki, a cheerful young man who treated Riku like his own younger brother. The man, who had a younger sibling of his own, proved to be a good teacher who was both kind and strict, earning Tenn's trust after a few study sessions.

As for the members of TRIGGER, all Alphas, who live with him are aware of his condition. In order to care for the child, they took measures to be able to resist an Omega's pheromones and other related matters, Tenn himself included. They were all fond of the sweet child and wanted to care for him the best way they can. However, if his heats were to get out of control, Tenn alone would handle the matter.

At the current moment in the present, Tenn was not home. Both him and the other member of the group, Tsunashi Ryuunosuke, had work to complete and would only be back in the evening. As such, Gaku was entrusted to watch after the child alone. The silver-haired man had no qualms with that, as the child would usually be doing his homework or reading a book from the huge collection Tenn had amassed for him.

Today, however, was not the same as any usual day.

After eating the meal that Ryuu had prepared for them before he left, Riku returned to his room to work on his math assignment. Gaku was in the living room, folding the laundry while watching a movie he rented from the nearby store. He was just done with the chore when a strong, familiar scent hit his senses. It was the sweet smell of an Omega's pheromones.

Without having to check on the child, Gaku knew what had happened: Riku had gone into heat.

He had nothing but a bad feeling about it, but quickly rushed towards the child's room and slammed the door open without knocking. "Riku! Are you—"

It might have been a mistake to do so. When he entered the room, the pheromones were so potent that it nearly brought him to his knees; it took every bit of will in him just to be able to keep standing. It was the first time that his pheromones had been this strong, at least compared to what Gaku had experienced before.

"Gaku-nii..." The child, who was kneeling down on the floor, looked up at him with wet eyes and a reddened face.

"J-Just wait, okay? I'm going to call Tenn..."

To him, the child's scent was like what nectar was to a bee, a sweet aroma that overwhelmed all of his senses and making Gaku's heart race. It was hard to control the fierce impulse that began to rage through his entire system, which urged for him to just act, not think. It was making it hard for him to even take a step back, let alone remember where he had left his cell phone.

"Gaku-nii, it hurts..." The child, breathless and now in tears, was practically begging him. "Help me..."

With that, Gaku felt a certain thread in him snap.

"Riku, I'm sorry."

He lifted the red haired boy up in his arms as if he were a princess, earning a surprised yelp from the child. He sat down on the bed with the child on his lap but wasted no time pulling down his shorts and underwear, tossing the garments onto the floor. As expected, his penis was already hard and leaking precum. Curling his long fingers around it to grip it firmly but gently, Gaku began to stroke it. Unlike his own it was small, but that was expected from a child his age. However, it was just as sensitive; the sounds the child makes are his reactions to every little movement he makes, even a little shift of his finger.

Riku was clinging onto his shirt, holding onto him for support and security. His pants and breaths grew heavier as Gaku steadily increased his pace, bringing him closer to climax. Between pants, he called out the man's name in his high-pitched voice, a sweet sound that reminded him of a bird's chirp, only more erotic. These only grew louder as he approached the peak.

"Gaku-nii, I… I can't…"

At this time the entire room was filled with the overpowering scent of his pheromones; the Alpha was no longer able to resist it nor have any control over himself.

"Go ahead," Gaku whispered huskily into his ear, sending a shiver down the boy's spine. "Let it all out."

It was the trigger that he needed to surpass his limits, and he came with a sharp cry. He shot his first load over Gaku's hand, still wrapped around his member. However, one time was not sufficient for the heat to subside; he still hard even though he had just come moments ago.

Gaku brought his stained hand up to his mouth, his tongue darting out to lap up some of the thick white nectar. It was sweet but mild, yet it was a taste he could get addicted to. Just like vanilla.

More.

This was not enough to satisfy him.

He needed more.

"Kyah!" Riku let out a yelp when Gaku buried his nose into the crook of his neck and inhaled deeply.

However, he did not stop at that. He ran his tongue along his neck up to his jaw. He could feel the child's soft, supple skin, something one would never . As expected, even his scent and sweat were sweet to his senses; he had never experienced anything like this before.

"Gaku-nii...?" The boy sounded scared, his voice trembling just as his body was. "N-No... I don't want this..."

Instead of bringing the Alpha back to his senses, the protest only served to stir him up even further. In almost an instant, he slid the child off his lap, dropping him onto the bed.

The mattress was soft and the impact was not great, but the sudden movement had astonished little Riku. However, what made him more surprised was when Gaku himself climbed onto the bed. The man had him pinned down, with his hands pressed down onto the mattress by his sides and his knee between his spread legs.

When Riku looked down, he noticed the bulge between Gaku's legs that made his pants look extremely uncomfortable. It was not a brand new sight to him; he had seen Tenn have the same reaction before. However, Tenn never did anything without his consent, hence what was happening now was completely new to him. He could try to push him away, futile as the attempt would be, but it was not simply due to physical differences. His body was already under the influence to the Alpha's pheromones, released as a biological response to his own. And even though he was frightened, the discomfort of his heat was making him unable to think and fight back.

Regardless, Gaku continued. He trailed his fingertips from the redhead's belly down to the area between his legs, where the Omega's most sensitive spots were. He rubbed the folds in a circular motion, occasionally brushing his fingers across the opening to tease the child. He may be infertile, but like most Omegas he has developed certain parts of the reproductive system that facilitates pregnancy and childbirth.

It was cute, Gaku thought, how the child was responding to his teasing. Coming once made him more sensitive to even the faintest touch. It was not long before Riku had his second ejaculation, which followed after he slid his forefinger between the folds.

However, the Alpha completely ignored this, moving his finger to gauge the tightness of the orifice. The walls of muscle clamped down on the digit as if resisting the intrusion. However, the canal was already lubricated as an effect of his heat and he could move it much too easily. He was able to add a second with little difficulty and began moving them in a scissoring motion, stretching the cavern open. He was not able to estimate how deep they could go, but by common sense, it would be relatively shallow.

He may not be able to fit his entire length in, but that fact alone is not going to stop him after he had gone this far.

A third finger was inserted, continuing to stretch him out even further. As he did, he used his free hand to lift the boy's yellow T-shirt up, exposing his pert nipples. One he took into his mouth, prodding and lapping; the other he entertained with his fingers, pinching and rubbing to stimulate the erect bud.

From this, the boy came once more. However, he is now ready and prepared to receive Gaku.

Prying himself away from the boy, the Alpha quickly undid his belt to remove his jeans, along with the rest of his clothes including his T-shirt and underwear. The child could not help but to stare at the man's crotch, specifically his now proudly exposed erection.

"It's bigger than Tenn-nii's..." Riku could not help but remark.

Will that even fit in him?

No, it would not, he was convinced. He had already considered Tenn's to be big; comparing to that the one in front of him was simply enormous. It would most likely rip him apart, and it would hurt really badly.

However, what scared him the most was not the prospect of unbearable pain. Instead, it was the fact that, unlike his mind, his body was anticipating its entry; more than it did with his beloved older brother.

"No... No! I don't want this! Tenn-nii! Help me!"

"It's no use calling for him. There's no one else here to save you."

For a moment Gaku had the mind to consider putting on a condom, but his dick was already twitching impatiently as if yelling at him to stop dwelling and stick it into the child. Besides, it's not like he knew where Tenn kept those anyway, so it could not be helped.

It was hard to enter with the boy thrashing about, so Gaku had to use one hand to hold his wrists above his head. Since his legs were still spread and on each side of the adult being kicked was not a threat.

"Prepare yourself." The Alpha growled into his ear, lining himself with Riku's entrance.

He pushed the tip of his erection in without waiting for a reply, letting out a low groan when the cavern took the entire head in. It was tight, yet the warmth that enveloped his manhood was comfortable in the most unbearable way. This was better than anything he had ever experienced before.

Gaku continued pushing in until he hit something that prevented him from going in further; the cervix, if he had to guess. The boy's cry of pain was the alert to this maximum point, despite having barely half of him inside.

Perhaps it was in his instinct to be gentle, but he did not do anything until the child was used to his thick girth. Riku was clinging onto the sheets with so much force that his knuckles were turning white, as his heavy chest heaved up and down in an unsteady rhythm. Maybe going all the way was a bad idea, but there was no other way for the heat to subside.

When the boy was able to catch his breath and breathe normally, it was the sign that it was okay to continue. Just for good measure, Gaku thought that he should inform him before doing anything. "I'm going to move."

Despite having the courtesy to tell him that, once again he proceeded without acknowledgement. He had waited far too long for this; it was difficult to endure it for even a second longer. He withdrew himself, but before the tip could be removed he rammed it back into Riku, causing him to let out a startled yelp. He began with slow, shallow thrusts, only increasing both his pace and the depth of his thrusts gradually.

With each deep thrust, the boy moaned and mewled, overcome with a pleasure so great it drowned out all his senses, including the pain of being fucked raw and hard, which he was not used to. He came before Gaku, who followed several thrusts after feeling the already-tight canal clamp down on his erection. He shot his entire load into him, the walls of muscle draining every single drop from him.

However, that was not the end. Riku had not gotten over his heat and Gaku was still hard, the latter stimulated by the Omega's pheromones. The thrusts continued, and the process repeated itself several times more before the boy's heat finally subsided.

By that time both of them were drained of their energy. The exhaustion coupled with the sudden decrease in pheromones, which had served as the stimulus that induced his arousal, caused the man to black out momentarily. He regained consciousness soon after, but his head was throbbing as his mind tried to reorientate itself to what had happened.

To be honest, Gaku was not sure how many more times he came after the first. However, it was a rude shock when his mind finally cleared and he was able to regain some sense of himself, especially when he found himself buck naked next to the eight-year-old. There were stains from the tears that streamed down his face, and to summarise how he looked neck down he was a complete wreck.

The first thing that came to his attention, however, was the sight of his own sperm dribbling out of the slit between the child's legs in the most obscene manner that put rental porn videos to shame.

That, along with the realisation of what he had done, was more than enough to send him into a full-blown panic.

"Oh my fucking God."

Tenn is going to kill him.

Rather, he is going to torture him, slice him open and take out his guts before leaving him to die a slow and painful death.

What should he do?

What can he do?

What is he to do?

He does not know, and he can barely think about it.

For the first time in his life, Gaku had never been so worried and anxious.

He just fucked his groupmate's younger brother! A freaking child younger than him by fourteen years! For heaven's sake! He was no paedophile and the pheromones were certainly to blame, but still!

What the hell was he thinking?!

No, he actually was not thinking at all, but still! Still!

"Gaku-nii?"

The child calling him so innocently only made him feel more guilty about the entire matter.

"R-Riku, I..." There were so many thoughts racing through his mind, he could not even form the words needed to apologise to the child.

However, it seemed that Riku knew what he had wanted to say and gave him his usual bright smile. "It's okay. I'm better now so it's fine."

"No, it's not. Tenn will murder me."

"He won't; Gaku-nii was gentle, just like how Tenn-nii usually is."

"I know you're trying to comfort me, but it's not making me any better, you know. Do you even know how scary your brother is?"

"If we both keep this a secret from Tenn-nii, he won't know!"

"... I can see how the two of you are related."

The child flashed him a wide-toothed smile in return. With a younger brother this adorable, Gaku felt like he could understand why Tenn tends to be so overprotective of him. One would think that that would make Riku completely dependent on his brother, but now it seems like the older boy is the one who relies too much on the younger.

"Gaku-nii, isn't bath time soon?"

Glancing over at the wall clock by the door, Gaku realised how late it has become. "You're right. We should get everything cleaned up before the other two get back. I'll go get the bath filled, so go grab your pyjamas and underpants; I'll call you when we're done."

"Can we get in the tub together?"

"... Kid, please don't increase the weight of my sins."

Regardless of what he had said, they got in together for the safety of the child, who had a history of slipping on the wet tiled floor too many times in the even under the supervision of others. After they were done, the child was allowed to read before his bedtime. He had made himself comfortable on the couch with a mug of hot cocoa while Gaku quickly cleaned up the signs of everything that had happened earlier this evening.

Fortunately, he was done by the time the demon returned home.

"We're back!" Ryuu called out the moment the front door opened. "We brought ingredients for breakfast, too!"

Tenn-nii! Ryuu-nii! Welcome home!"

"We're home, Riku." After removing his shoes, Tenn picked up the child for a hug and a welcome home kiss on the cheek. "Did you finish your homework?"

"We're back." Ryuu, who was holding two bags from the supermarket, gave the child a smile as he walked past the pair. "I'll go put the groceries in the refrigerator first."

"Yup!" The child giggled in reply to the question as Tenn returned his kiss on his chubby cheek. However, the older of the Kujou brothers did not put him back down, instead, he held him closer to his body. "Err, Tenn-nii? Is something the matter?"

"Riku, did you use a different shampoo?"

Crap, Gaku cringed as he heard Tenn's question. As expected, the damned brat was sharp! "He ran out of his usual shampoo, that's all. I lent him mine to use."

"Really? But I just bought a new bottle of the kiddy shampoo yesterday, the strawberry-banana scented one."

"Ryuu!" Gaku growled at the man to keep his mouth shut.

While poor Ryuu was confused as to why he got scolded for simply stating the truth, Tenn being Tenn had caught on.

"Riku?" His voice was dripping with menace, even though he was still wearing the smiling face of angel's. "Did Gaku do something to you?"

"N-No, he didn't!" Riku, despite looking intimidated, still tried his best to protect Gaku. It made the adult feel guilty but his life, or death, depended on this. "We only got into the bath together!"

"Really?"

"Really!"

"Hmm..." Tenn hummed, seemingly understanding, but Gaku could tell that he was not convinced at all.

Ryuu, who had gotten the gist of the situation, decided to remove the child from the tense atmosphere the situation had brought upon them. "Ah, I almost forgot! Riku-kun, Tenn bought you some pudding for you on the way home as a special treat for working hard on your homework. Why don't you go wash your hands and eat it before you sleep?"

"Pudding!" The child clapped his hands in joy as Tenn let him down. "Thank you, Tenn-nii!"

"Anything for you, my dear." Tenn sent the child off cheerfully, but the moment Riku and Ryuu were out of sight he pointed his finger at Gaku, still wearing the serene expression on his face. However, his aura was similar to that of a furious war deity. "You. My room. Now."

As expected, he found out!

"Look, Tenn, there's a reason for all this."

"No excuses. Move."

"He was in heat! What was I supposed to do?"

"For one, you could have contacted me." Tenn grabbed Gaku by the collar, proceeding to drag him towards his room. "Now, let's handle this inside and... talk, like proper adults."

"You have no intention of talking at all, do you?"

"Who knows? But I'm a pacifist, you know, so I won't do anything to hurt you."

"Lies! I can tell from the look in your eyes!"

The last thing that can be heard before the shutting of the door was Gaku's cry of help, which sounded as if he was being dragged into hell.

"Will Gaku-nii be fine?" From the dining table, Riku could see everything that was going on and could not help but worry. "Tenn-nii looked really angry..."

"He'll be fine. I think." Ryuu tried to ease the awkwardness he was feeling with a laugh. "But Gaku is right; it can't be helped if it was an emergency. I'll go check on them later, just to make sure, so why don't you finish your pudding, brush your teeth and head straight to bed? I'll read you a bedtime story in Tenn's stead tonight."

"Yay!"

For a moment, Ryuu wondered what he would have done if he were in Gaku's position. However, the thought of getting skinned alive by Tenn, or its equivalent, was enough to deter him from the topic altogether. This was something he would only know when it actually happens, so it was best not to dwell on it.

Especially when he hopes that it would never happen.

Well, as long as what Gaku did does not have any effect on the child, in the long run, Tenn should not have anything to worry about.

"You know, Ryuu-nii, I was just thinking..."

"What is it?"

"... I wonder if Tenn-nii would let it out in me, too, next time. It felt really good."

"..." Okay, maybe there was a cause of concern after all. "Riku-kun, let's not touch on that topic, shall we?"

Now, to hope that that statement would never reach Tenn's ears.

**\- END -**


End file.
